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<h1><img src="../../../../boost.png" alt="Boost logo" align=
"middle" width="277" height="86">Boost.Flyweight
Factories reference</h1>

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<h2>Contents</h2>

<ul>
  <li><a href="#factory">Factories and factory specifiers</a></li>
  <li><a href="#factory_tag_synopsis">Header
    <code>"boost/flyweight/factory_tag.hpp"</code> synopsis</a>
    <ul>
      <li><a href="#is_factory">Class template <code>is_factory</code></a></li>
      <li><a href="#factory_construct">Class template <code>factory</code></a></li>
    </ul>    
  </li>
  <li><a href="#hashed_factory_fwd_synopsis">Header
    <code>"boost/flyweight/hashed_factory_fwd.hpp"</code> synopsis</a>
  </li>
  <li><a href="#hashed_factory_synopsis">Header
    <code>"boost/flyweight/hashed_factory.hpp"</code> synopsis</a>
    <ul>
      <li><a href="#hashed_factory_class">Class template <code>hashed_factory_class</code></a></li>
      <li><a href="#hashed_factory">Class template <code>hashed_factory</code></a></li>
    </ul>    
  </li>
  <li><a href="#set_factory_fwd_synopsis">Header
    <code>"boost/flyweight/set_factory_fwd.hpp"</code> synopsis</a>
  </li>
  <li><a href="#set_factory_synopsis">Header
    <code>"boost/flyweight/set_factory.hpp"</code> synopsis</a>
    <ul>
      <li><a href="#set_factory_class">Class template <code>set_factory_class</code></a></li>
      <li><a href="#set_factory">Class template <code>set_factory</code></a></li>
    </ul>    
  </li>
  <li><a href="#assoc_container_factory_fwd_synopsis">Header
    <code>"boost/flyweight/assoc_container_factory_fwd.hpp"</code> synopsis</a>
  </li>
  <li><a href="#assoc_container_factory_synopsis">Header
    <code>"boost/flyweight/assoc_container_factory.hpp"</code> synopsis</a>
    <ul>
      <li><a href="#assoc_container_factory_class">Class template <code>assoc_container_factory_class</code></a></li>
      <li><a href="#assoc_container_factory">Class template <code>assoc_container_factory</code></a></li>
    </ul>    
  </li>
</ul>

<h2><a name="factory">Factories and factory specifiers</a></h2>

<p>
Given a type <code>Key</code> and an
<a href="https://boost.org/sgi/stl/Assignable.html"><code>Assignable</code></a>
type <code>Entry</code> implicitly convertible to <code>const Key&amp;</code>, a
<i>factory of <code>Entry</code> elements</i> (implicitly associated to
<code>Key</code>) is a
<a href="https://boost.org/sgi/stl/DefaultConstructible.html"><code>Default
Constructible</code></a> entity able to store and retrieve immutable elements of
type <code>Entry</code>. A factory is governed by an associated equivalence
relation defined on <code>Key</code> so that no two
<code>Entry</code> objects convertible to equivalent <code>Key</code>s
can be stored simultaneously in the factory. Different factory types can
use different equivalence relations.
</p>

<p>
In the following table, <code>Factory</code> is a factory of elements
of type <code>Entry</code>, <code>f</code> denotes an object of type <code>Factory</code>,
<code>x</code> is an object of type <code>Entry</code> and <code>h</code> is a
value of <code>Factory::handle_type</code>.
</p>

<p align="center">
<table cellspacing="0">
  <caption><b>Factory requirements.</b></caption>
<tr>
  <th align="center">expression</th>
  <th align="center">return type</th>
  <th align="center">assertion/note<br>pre/post-condition</th>
</tr>
<tr>
  <td><code>Factory::handle_type</code></td>
  <td>handle to elements of type <code>T</code><br>
    stored in the factory
  </td>
  <td><code>handle_type</code> is
    <a href="https://boost.org/sgi/stl/Assignable.html"><code>Assignable</code></a>
    and its copy and<br>
    assignment operations never throw an exception.
  </td>
</tr>
<tr class="odd_tr">
  <td><code>f.insert(x);</code></td>
  <td><code>handle_type</code></td>
  <td>Inserts a copy of <code>x</code> if there is no equivalent entry in <code>f</code>;<br>
    returns a handle to the inserted or equivalent element.
  </td>
</tr>
<tr>
  <td><code>f.erase(h);</code></td>
  <td><code>void</code></td>
  <td>Erases the element associated to <code>h</code>.<br>
   This operation does not throw.
  </td>
</tr>
<tr class="odd_tr">
  <td><code>f.entry(h);</code></td>
  <td><code>const Entry&amp;</code></td>
  <td>Returns a reference to the element associated to <code>h</code>.<br>
    This operation does not throw.
  </td>
</tr>
</table>
</p>

<p>
Additionally to the basic thread safety guarantee which is implicitly assumed
for most classes including the majority of components of the
C++ standard library, it is required that the member function <code>entry</code>
can be invoked simultaneously from different threads, even in the presence
of concurrent accesses to <code>insert</code> and <code>erase</code> (as long
as the entry returned by <code>entry</code> is not the one which is being
erased).
</p>

<p>
A type <code>S</code> is said to be a <i>factory specifier</i> if:
<ol>
  <li>One of the following conditions is satisfied:
    <ol type="a">
      <li><a href="#is_factory"><code>is_factory&lt;S&gt;::type</code></a> is
      <a href="../../../mpl/doc/refmanual/bool.html"><code>boost::mpl::true_</code></a>,</li>
      <li><code>S</code> is of the form <a href="#factory_construct"><code>factory&lt;S'&gt;</code></a>.</li>
    </ol>
  </li>
  <li><code>S</code>, or <code>S'</code> if (b) applies, is an
    <a href="../../../mpl/doc/refmanual/lambda-expression.html"><code>MPL Lambda
    Expression</code></a> such that invoking it with types (<code>Entry</code>,
    <code>Key</code>) resolves to a factory type of <code>Entry</code> elements
    (implicitly associated to <code>Key</code>).
  </li>
</ol>
</p>

<h2><a name="factory_tag_synopsis">Header
<a href="../../../../boost/flyweight/factory_tag.hpp"><code>"boost/flyweight/factory_tag.hpp"</code></a> synopsis</a></h2>

<blockquote><pre>
<span class=keyword>namespace</span> <span class=identifier>boost</span><span class=special>{</span>

<span class=keyword>namespace</span> <span class=identifier>flyweights</span><span class=special>{</span>

<span class=keyword>struct</span> <span class=identifier>factory_marker</span><span class=special>;</span>

<span class=keyword>template</span><span class=special>&lt;</span><span class=keyword>typename</span> <span class=identifier>T</span><span class=special>&gt;</span>
<span class=keyword>struct</span> <span class=identifier>is_factory</span><span class=special>;</span>

<span class=keyword>template</span><span class=special>&lt;</span><span class=keyword>typename</span> <span class=identifier>T</span><span class=special>&gt;</span>
<span class=keyword>struct</span> <span class=identifier>factory</span><span class=special>;</span>

<span class=special>}</span> <span class=comment>// namespace boost::flyweights</span>

<span class=special>}</span> <span class=comment>// namespace boost</span>
</pre></blockquote>

<h3><a name="is_factory">Class template <code>is_factory</code></a></h3>

<p>
Unless specialized by the user, <code>is_factory&lt;T&gt;::type</code> is
<a href="../../../mpl/doc/refmanual/bool.html"><code>boost::mpl::true_</code></a>
if <code>T</code> is derived from <code>factory_marker</code>, and it is
<a href="../../../mpl/doc/refmanual/bool.html"><code>boost::mpl::false_</code></a>
otherwise.
</p>

<h3><a name="factory_construct">Class template <code>factory</code></a></h3>

<p>
<code>factory&lt;T&gt;</code> is a syntactic construct meant to indicate
that <code>T</code> is a factory specifier without resorting to the
mechanisms provided by the <code>is_factory</code> class template.
</p>

<h2><a name="hashed_factory_fwd_synopsis">Header
<a href="../../../../boost/flyweight/hashed_factory_fwd.hpp"><code>"boost/flyweight/hashed_factory_fwd.hpp"</code></a> synopsis</a></h2>

<blockquote><pre>
<span class=keyword>namespace</span> <span class=identifier>boost</span><span class=special>{</span>

<span class=keyword>namespace</span> <span class=identifier>flyweights</span><span class=special>{</span>

<span class=keyword>template</span><span class=special>&lt;</span>
  <span class=keyword>typename</span> <span class=identifier>Entry</span><span class=special>,</span><span class=keyword>typename</span> <span class=identifier>Key</span><span class=special>,</span>
  <span class=keyword>typename</span> <span class=identifier>Hash</span><span class=special>=</span><b>implementation defined</b><span class=special>,</span>
  <span class=keyword>typename</span> <span class=identifier>Pred</span><span class=special>=</span><b>implementation defined</b><span class=special>,</span>
  <span class=keyword>typename</span> <span class=identifier>Allocator</span><span class=special>=</span><b>implementation defined</b>
<span class=special>&gt;</span>
<span class=keyword>class</span> <span class=identifier>hashed_factory_class</span><span class=special>;</span>

<span class=keyword>template</span><span class=special>&lt;</span>
  <span class=keyword>typename</span> <span class=identifier>Hash</span><span class=special>=</span><b>implementation defined</b><span class=special>,</span>
  <span class=keyword>typename</span> <span class=identifier>Pred</span><span class=special>=</span><b>implementation defined</b><span class=special>,</span>
  <span class=keyword>typename</span> <span class=identifier>Allocator</span><span class=special>=</span><b>implementation defined</b>
<span class=special>&gt;</span>
<span class=keyword>struct</span> <span class=identifier>hashed_factory</span><span class=special>;</span>

<span class=special>}</span> <span class=comment>// namespace boost::flyweights</span>

<span class=special>}</span> <span class=comment>// namespace boost</span>
</pre></blockquote>

<p>
<code>hashed_factory_fwd.hpp</code> forward declares the class templates
<a href="#hashed_factory_class"><code>hashed_factory_class</code></a>
and <a href="#hashed_factory"><code>hashed_factory</code></a>.
</p>

<h2><a name="hashed_factory_synopsis">Header
<a href="../../../../boost/flyweight/hashed_factory.hpp"><code>"boost/flyweight/hashed_factory.hpp"</code></a> synopsis</a></h2>

<h3><a name="hashed_factory_class">Class template <code>hashed_factory_class</code></a></h3>

<p>
<code>hashed_factory_class</code> is a <a href="#factory"><code>Factory</code></a>
implemented with a hashed container.
</p>

<blockquote><pre>
<span class=keyword>template</span><span class=special>&lt;</span>
  <span class=keyword>typename</span> <span class=identifier>Entry</span><span class=special>,</span><span class=keyword>typename</span> <span class=identifier>Key</span><span class=special>,</span>
  <span class=keyword>typename</span> <span class=identifier>Hash</span><span class=special>,</span><span class=keyword>typename</span> <span class=identifier>Pred</span><span class=special>,</span><span class=keyword>typename</span> <span class=identifier>Allocator</span>
<span class=special>&gt;</span>
<span class=keyword>class</span> <span class=identifier>hashed_factory_class</span>
<span class=special>{</span>
<span class=keyword>public</span><span class=special>:</span>
  <span class=keyword>typedef</span> <b>implementation defined</b> <span class=identifier>handle_type</span><span class=special>;</span>
  
  <span class=identifier>handle_type</span>  <span class=identifier>insert</span><span class=special>(</span><span class=keyword>const</span> <span class=identifier>Entry</span><span class=special>&amp;</span> <span class=identifier>x</span><span class=special>);</span>
  <span class=keyword>void</span>         <span class=identifier>erase</span><span class=special>(</span><span class=identifier>handle_type</span> <span class=identifier>h</span><span class=special>);</span>
  <span class=keyword>const</span> <span class=identifier>Entry</span><span class=special>&amp;</span> <span class=identifier>entry</span><span class=special>(</span><span class=identifier>handle_type</span> <span class=identifier>h</span><span class=special>);</span>
<span class=special>};</span>
</pre></blockquote>

<p>
<code>Hash</code> is a
<a href="https://boost.org/sgi/stl/DefaultConstructible.html"><code>Default
Constructible</code></a>
<a href="https://boost.org/sgi/stl/UnaryFunction.html"><code>Unary Function</code></a>
taking a single argument of type <code>Key</code> and returning a
value of type <code>std::size_t</code> in the range
<code>[0, std::numeric_limits&lt;std::size_t&gt;::max())</code>.
<code>Pred</code> is a
<a href="https://boost.org/sgi/stl/DefaultConstructible.html"><code>Default
Constructible</code></a> 
<a href="https://boost.org/sgi/stl/BinaryPredicate.html">
<code>Binary Predicate</code></a> inducing an equivalence relation
on elements of <code>Key</code>. It is required that
a <code>Hash</code> object return the same value for objects
equivalent under <code>Pred</code>.
The equivalence relation on <code>Key</code> associated to the factory is
that induced by <code>Pred</code>.
The default arguments for <code>Hash</code> and <code>Pred</code> are
<a href="../../../functional/hash/index.html"><code>boost::hash&lt;Key&gt;</code></a>
and <code>std::equal_to&lt;Key&gt;</code>, respectively. 
<code>Allocator</code> must be an allocator of <code>Entry</code> objects
satisfying the associated C++ requirements at <b>[lib.allocator.requirements]</b>. 
The default argument is <code>std::allocator&lt;Entry&gt;</code>. The internal
hashed container upon which <code>hashed_factory_class</code> is based is
constructed with default initialized objects of type <code>Hash</code>,
<code>Pred</code> and <code>Allocator</code>.
</p>

<h3><a name="hashed_factory">Class template <code>hashed_factory</code></a></h3>

<p>
<a href="#factory"><code>Factory Specifier</code></a> for <a href="#hashed_factory_class"><code>hashed_factory_class</code></a>.
</p>

<blockquote><pre>
<span class=keyword>template</span><span class=special>&lt;</span><span class=keyword>typename</span> <span class=identifier>Hash</span><span class=special>,</span><span class=keyword>typename</span> <span class=identifier>Pred</span><span class=special>,</span><span class=keyword>typename</span> <span class=identifier>Allocator</span><span class=special>&gt;</span>
<span class=keyword>struct</span> <span class=identifier>hashed_factory</span><span class=special>;</span>
</pre></blockquote>

<p>
<code>hashed_factory&lt;Hash,Pred,Allocator&gt;</code> is an
<a href="../../../mpl/doc/refmanual/metafunction-class.html"><code>MPL Metafunction
Class</code></a> such that the type
</p>

<blockquote><pre>
<span class=identifier>boost</span><span class=special>::</span><span class=identifier>mpl</span><span class=special>::</span><span class=identifier>apply</span><span class=special>&lt;</span>
  <span class=identifier>hashed_factory</span><span class=special>&lt;</span><span class=identifier>Hash</span><span class=special>,</span><span class=identifier>Pred</span><span class=special>,</span><span class=identifier>Allocator</span><span class=special>&gt;,</span>
  <span class=identifier>Entry</span><span class=special>,</span><span class=identifier>Key</span>
<span class=special>&gt;::</span><span class=identifier>type</span>
</pre></blockquote>

<p>
is the same as
</p>

<blockquote><pre>
<span class=identifier>boost</span><span class=special>::</span><span class=identifier>mpl</span><span class=special>::</span><span class=identifier>apply</span><span class=special>&lt;</span>
  <span class=identifier>hashed_factory_class</span><span class=special>&lt;</span><span class=identifier>boost</span><span class=special>::</span><span class=identifier>mpl</span><span class=special>::</span><span class=identifier>_1</span><span class=special>,</span><span class=identifier>boost</span><span class=special>::</span><span class=identifier>mpl</span><span class=special>::</span><span class=identifier>_2</span><span class=special>,</span><span class=identifier>Hash</span><span class=special>,</span><span class=identifier>Pred</span><span class=special>,</span><span class=identifier>Allocator</span><span class=special>&gt;,</span>
  <span class=identifier>Entry</span><span class=special>,</span><span class=identifier>Key</span>
<span class=special>&gt;::</span><span class=identifier>type</span>
</pre></blockquote>

<p>
This implies that <code>Hash</code>, <code>Pred</code> and <code>Allocator</code>
can be 
<a href="../../../mpl/doc/refmanual/placeholder-expression.html"><code>MPL
Placeholder Expressions</code></a> resolving to the actual types used by
<code>hashed_factory_class</code>.
</p>

<h2><a name="set_factory_fwd_synopsis">Header
<a href="../../../../boost/flyweight/set_factory_fwd.hpp"><code>"boost/flyweight/set_factory_fwd.hpp"</code></a> synopsis</a></h2>

<blockquote><pre>
<span class=keyword>namespace</span> <span class=identifier>boost</span><span class=special>{</span>

<span class=keyword>namespace</span> <span class=identifier>flyweights</span><span class=special>{</span>

<span class=keyword>template</span><span class=special>&lt;</span>
  <span class=keyword>typename</span> <span class=identifier>Entry</span><span class=special>,</span><span class=keyword>typename</span> <span class=identifier>Key</span><span class=special>,</span>
  <span class=keyword>typename</span> <span class=identifier>Compare</span><span class=special>=</span><b>implementation defined</b><span class=special>,</span>
  <span class=keyword>typename</span> <span class=identifier>Allocator</span><span class=special>=</span><b>implementation defined</b>
<span class=special>&gt;</span>
<span class=keyword>class</span> <span class=identifier>set_factory_class</span><span class=special>;</span>

<span class=keyword>template</span><span class=special>&lt;</span>
  <span class=keyword>typename</span> <span class=identifier>Compare</span><span class=special>=</span><b>implementation defined</b><span class=special>,</span>
  <span class=keyword>typename</span> <span class=identifier>Allocator</span><span class=special>=</span><b>implementation defined</b>
<span class=special>&gt;</span>
<span class=keyword>struct</span> <span class=identifier>set_factory</span><span class=special>;</span>

<span class=special>}</span> <span class=comment>// namespace boost::flyweights</span>

<span class=special>}</span> <span class=comment>// namespace boost</span>
</pre></blockquote>

<p>
<code>set_factory_fwd.hpp</code> forward declares the class templates
<a href="#set_factory_class"><code>set_factory_class</code></a>
and <a href="#set_factory"><code>set_factory</code></a>.
</p>

<h2><a name="set_factory_synopsis">Header
<a href="../../../../boost/flyweight/set_factory.hpp"><code>"boost/flyweight/set_factory.hpp"</code></a> synopsis</a></h2>

<h3><a name="set_factory_class">Class template <code>set_factory_class</code></a></h3>

<p>
<code>set_factory_class</code> is a <a href="#factory"><code>Factory</code></a>
implemented on top of an orderded associative container.
</p>

<blockquote><pre>
<span class=keyword>template</span><span class=special>&lt;</span>
  <span class=keyword>typename</span> <span class=identifier>Entry</span><span class=special>,</span><span class=keyword>typename</span> <span class=identifier>Key</span><span class=special>,</span>
  <span class=keyword>typename</span> <span class=identifier>Compare</span><span class=special>,</span><span class=keyword>typename</span> <span class=identifier>Allocator</span>
<span class=special>&gt;</span>
<span class=keyword>class</span> <span class=identifier>set_factory_class</span>
<span class=special>{</span>
<span class=keyword>public</span><span class=special>:</span>
  <span class=keyword>typedef</span> <b>implementation defined</b> <span class=identifier>handle_type</span><span class=special>;</span>
  
  <span class=identifier>handle_type</span>  <span class=identifier>insert</span><span class=special>(</span><span class=keyword>const</span> <span class=identifier>Entry</span><span class=special>&amp;</span> <span class=identifier>x</span><span class=special>);</span>
  <span class=keyword>void</span>         <span class=identifier>erase</span><span class=special>(</span><span class=identifier>handle_type</span> <span class=identifier>h</span><span class=special>);</span>
  <span class=keyword>const</span> <span class=identifier>Entry</span><span class=special>&amp;</span> <span class=identifier>entry</span><span class=special>(</span><span class=identifier>handle_type</span> <span class=identifier>h</span><span class=special>);</span>
<span class=special>};</span>
</pre></blockquote>

<p>
<code>Compare</code> is a 
<a href="https://boost.org/sgi/stl/DefaultConstructible.html"><code>Default
Constructible</code></a>
<a href="https://boost.org/sgi/stl/StrictWeakOrdering.html">
<code>Strict Weak Ordering</code></a> on <code>Key</code>. Two <code>Key</code>s
<code>x</code> and <code>y</code> are considered equivalent if
<code>!c(x,y)&amp;&amp;!c(y,x)</code> for <code>c</code> of type <code>Compare</code>.
The default argument of <code>Compare</code> is <code>std::less&lt;Key&gt;</code>.
<code>Allocator</code> must be an allocator of <code>Entry</code> objects
satisfying the associated C++ requirements at <b>[lib.allocator.requirements]</b>. 
The default argument is <code>std::allocator&lt;Entry&gt;</code>. The internal
container upon which <code>set_factory_class</code> is based is
constructed with default initialized objects of type <code>Compare</code>
and <code>Allocator</code>.
</p>

<h3><a name="set_factory">Class template <code>set_factory</code></a></h3>

<p>
<a href="#factory"><code>Factory Specifier</code></a> for <a href="#set_factory_class"><code>set_factory_class</code></a>.
</p>

<blockquote><pre>
<span class=keyword>template</span><span class=special>&lt;</span><span class=keyword>typename</span> <span class=identifier>Compare</span><span class=special>,</span><span class=keyword>typename</span> <span class=identifier>Allocator</span><span class=special>&gt;</span>
<span class=keyword>struct</span> <span class=identifier>set_factory</span><span class=special>;</span>
</pre></blockquote>

<p>
<code>set_factory&lt;Compare,Allocator&gt;</code> is an
<a href="../../../mpl/doc/refmanual/metafunction-class.html"><code>MPL Metafunction
Class</code></a> such that the type
</p>

<blockquote><pre>
<span class=identifier>boost</span><span class=special>::</span><span class=identifier>mpl</span><span class=special>::</span><span class=identifier>apply</span><span class=special>&lt;</span>
  <span class=identifier>set_factory</span><span class=special>&lt;</span><span class=identifier>Compare</span><span class=special>,</span><span class=identifier>Allocator</span><span class=special>&gt;,</span>
  <span class=identifier>Entry</span><span class=special>,</span><span class=identifier>Key</span>
<span class=special>&gt;::</span><span class=identifier>type</span>
</pre></blockquote>

<p>
is the same as
</p>

<blockquote><pre>
<span class=identifier>boost</span><span class=special>::</span><span class=identifier>mpl</span><span class=special>::</span><span class=identifier>apply</span><span class=special>&lt;</span>
  <span class=identifier>set_factory_class</span><span class=special>&lt;</span><span class=identifier>boost</span><span class=special>::</span><span class=identifier>mpl</span><span class=special>::</span><span class=identifier>_1</span><span class=special>,</span><span class=identifier>boost</span><span class=special>::</span><span class=identifier>mpl</span><span class=special>::</span><span class=identifier>_2</span><span class=special>,</span><span class=identifier>Compare</span><span class=special>,</span><span class=identifier>Allocator</span><span class=special>&gt;,</span>
  <span class=identifier>Entry</span><span class=special>,</span><span class=identifier>Key</span>
<span class=special>&gt;::</span><span class=identifier>type</span>
</pre></blockquote>

<p>
This implies that <code>Compare</code> and <code>Allocator</code>
can be 
<a href="../../../mpl/doc/refmanual/placeholder-expression.html"><code>MPL
Placeholder Expressions</code></a> resolving to the actual types used by
<code>set_factory_class</code>.
</p>

<h2><a name="assoc_container_factory_fwd_synopsis">Header
<a href="../../../../boost/flyweight/assoc_container_factory_fwd.hpp"><code>"boost/flyweight/assoc_container_factory_fwd.hpp"</code></a> synopsis</a></h2>

<blockquote><pre>
<span class=keyword>namespace</span> <span class=identifier>boost</span><span class=special>{</span>

<span class=keyword>namespace</span> <span class=identifier>flyweights</span><span class=special>{</span>

<span class=keyword>template</span><span class=special>&lt;</span><span class=keyword>typename</span> <span class=identifier>Container</span><span class=special>&gt;</span>
<span class=keyword>class</span> <span class=identifier>assoc_container_factory_class</span><span class=special>;</span>

<span class=keyword>template</span><span class=special>&lt;</span><span class=keyword>typename</span> <span class=identifier>ContainerSpecifier</span><span class=special>&gt;</span>
<span class=keyword>struct</span> <span class=identifier>assoc_container_factory</span><span class=special>;</span>

<span class=special>}</span> <span class=comment>// namespace boost::flyweights</span>

<span class=special>}</span> <span class=comment>// namespace boost</span>
</pre></blockquote>

<p>
<code>assoc_container_factory_fwd.hpp</code> forward declares the class templates
<a href="#assoc_container_factory_class"><code>assoc_container_factory_class</code></a>
and <a href="#assoc_container_factory"><code>assoc_container_factory</code></a>.
</p>

<h2><a name="assoc_container_factory_synopsis">Header
<a href="../../../../boost/flyweight/assoc_container_factory.hpp"><code>"boost/flyweight/assoc_container_factory.hpp"</code></a> synopsis</a></h2>

<h3><a name="assoc_container_factory_class">Class template <code>assoc_container_factory_class</code></a></h3>

<p>
<code>assoc_container_factory_class</code> wraps a suitable associative container
to provide a <a href="#factory"><code>Factory</code></a> interface.
</p>

<blockquote><pre>
<span class=keyword>template</span><span class=special>&lt;</span><span class=keyword>typename</span> <span class=identifier>Container</span><span class=special>&gt;</span>
<span class=keyword>class</span> <span class=identifier>assoc_container_factory_class</span>
<span class=special>{</span>
<span class=keyword>public</span><span class=special>:</span>
  <span class=keyword>typedef</span> <span class=keyword>typename</span> <span class=identifier>Container</span><span class=special>::</span><span class=identifier>iterator</span> <span class=identifier>handle_type</span><span class=special>;</span>
  
  <span class=identifier>handle_type</span> <span class=identifier>insert</span><span class=special>(</span><span class=keyword>const</span> <span class=keyword>typename</span> <span class=identifier>Container</span><span class=special>::</span><span class=identifier>value_type</span><span class=special>&amp;</span> <span class=identifier>x</span><span class=special>);</span>
  <span class=keyword>void</span>        <span class=identifier>erase</span><span class=special>(</span><span class=identifier>handle_type</span> <span class=identifier>h</span><span class=special>);</span>
  <span class=keyword>const</span> <span class=keyword>typename</span> <span class=identifier>Container</span><span class=special>::</span><span class=identifier>value_type</span><span class=special>&amp;</span> <span class=identifier>entry</span><span class=special>(</span><span class=identifier>handle_type</span> <span class=identifier>h</span><span class=special>);</span>
<span class=special>};</span>
</pre></blockquote>

<p>
<code>Container</code> must be an (ordered or unordered) associative container
such that
<ol>
  <li><code>Container::key_type</code> is the same as
    <code>Container::value_type</code> (which is the entry type associated to
    the factory).
  </li>
  <li>Unique keys (rather than equivalent keys) are supported.</li>
  <li><code>Container</code> is <i>stable</i>, i.e. its iterators are not
    invalidated upon insert or erase operations.</li>
</ol>
The equivalence relation associated to <code>assoc_container_factory_class</code>
is the one induced by <code>Container</code>. If equivalence of elements
of <code>Container::value_type</code> is determined solely on the basis of a
type <code>value_type'</code> to which <code>value_type</code> is
implicitly convertible, then <code>assoc_container_factory_class</code> is
a factory of entries of type <code>value_type</code> implicitly associated to
<code>value_type'</code>. For example, the instantiation
</p>

<blockquote><pre>
<span class=identifier>assoc_container_factory_class</span><span class=special>&lt;</span>
  <span class=identifier>std</span><span class=special>::</span><span class=identifier>set</span><span class=special>&lt;</span><span class=identifier>derived</span><span class=special>,</span><span class=identifier>std</span><span class=special>::</span><span class=identifier>less</span><span class=special>&lt;</span><span class=identifier>base</span><span class=special>&gt;</span> <span class=special>&gt;</span> <span class=comment>// derived inherits from base</span>
<span class=special>&gt;</span>
</pre></blockquote>

<p>
is a factory of <code>derived</code> elements implicitly associated to
<code>base</code>.
</p>

<h3><a name="assoc_container_factory">Class template <code>assoc_container_factory</code></a></h3>

<p>
<a href="#factory"><code>Factory Specifier</code></a> for <a href="#assoc_container_factory_class"><code>assoc_container_factory_class</code></a>.
</p>

<blockquote><pre>
<span class=keyword>template</span><span class=special>&lt;</span><span class=keyword>typename</span> <span class=identifier>ContainerSpecifier</span><span class=special>&gt;</span>
<span class=keyword>struct</span> <span class=identifier>assoc_container_factory</span><span class=special>;</span>
</pre></blockquote>

<p>
<code>ContainerSpecifier</code> must be an 
<a href="../../../mpl/doc/refmanual/lambda-expression.html"><code>MPL Lambda
Expression</code></a> resolving, when invoked with (<code>Entry</code>,
<code>Key</code>), to a type <code>Container</code> such that
<code>assoc_container_factory_class&lt;Container&gt;</code> is a factory
of <code>Entry</code> elements implicitly associated to <code>Key</code>.
</p>

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<p>Revised April 24th 2019</p>

<p>&copy; Copyright 2006-2019 Joaqu&iacute;n M L&oacute;pez Mu&ntilde;oz.
Distributed under the Boost Software 
License, Version 1.0. (See accompanying file <a href="../../../../LICENSE_1_0.txt">
LICENSE_1_0.txt</a> or copy at <a href="http://www.boost.org/LICENSE_1_0.txt">
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